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fedora-users: Re: Getting timeouts on TFTP on F15 as well as F14

Re: Getting timeouts on TFTP on F15 as well as F14

From: Aaron Gray <aaronngray.lists_at_nospam>
Date: Tue Oct 11 2011 - 12:24:52 GMT
To: Frantisek Hanzlik <franta@hanzlici.cz>

On 11 October 2011 13:13, Frantisek Hanzlik <franta@hanzlici.cz> wrote:

> Aaron Gray wrote:
> > On 11 October 2011 00:05, Frantisek Hanzlik <franta@hanzlici.cz <mailto:
> franta@hanzlici.cz>>
> > wrote:
> >
> > Aaron Gray wrote:
> > > On 10 October 2011 23:31, Frantisek Hanzlik <franta@hanzlici.cz
> > <mailto:franta@hanzlici.cz> <mailto:franta@hanzlici.cz <mailto:
> franta@hanzlici.cz>>>
> > > wrote:
> > >
> > > Aaron Gray wrote:
> > > > On 10 October 2011 22:20, Frantisek Hanzlik <
> franta@hanzlici.cz
> > <mailto:franta@hanzlici.cz>
> > > <mailto:franta@hanzlici.cz <mailto:franta@hanzlici.cz>>
> <mailto:franta@hanzlici.cz
> > <mailto:franta@hanzlici.cz> <mailto:franta@hanzlici.cz <mailto:
> franta@hanzlici.cz>>>>
> > > > wrote:
> > > >
> > > > Aaron Gray wrote:
> > > > ...
> > > > >
> > > > > 4) if You use firewall (iptables), You should load
> nf_conntrack_tftp module,
> > > > > for tracking ephemeral ports. That means
> /etc/sysconfig/iptables-config
> > should
> > > > > contain line as:
> > > > > ...
> > > > > IPTABLES_MODULES="nf_conntrack_tftp"
> > > > > ...
> > > > > (other module is for NATting tftp connection)
> > > > >
> > > > >
> > > > > using localhost
> > > >
> > > > loopback (lo interface) is subject to firewall rules too.
> And Your tcpdump
> > > > below show IP addresses 192.168.0.4 and 192.168.0.5 -
> they perhaps are not
> > > > at lo loopback interface?
> > > > Have You firewall active?
> > > >
> > > >
> > > > I wrote a firewall rule :-
> > > >
> > > > -A INPUT -m state --state NEW -m udp -p udp --dport 69 -j
> ACCEPT
> > >
> > > Then You should have (best at beginning of filter table rules)
> rule:
> > >
> > > -A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
> > >
> > >
> > > Okay.
> > >
> > >
> > >
> > > (and nf_conntrack_tftp module listed in
> "/etc/sysconfig/iptables-config",
> > > as I wrote before). You must restart iptables after these
> changes.
> >
> > Is nf_conntrack_tftp module loaded? You should obtain similar output:
> > # lsmod |grep tftp
> > nf_conntrack_tftp 3325 0
> > nf_conntrack 56162 4
> nf_conntrack_tftp,nf_conntrack_ipv4,nf_conntrack_ipv6,xt_state
> >
> >
> > No contrack_tftp running, but it is not needed with localhost TFTP test.
>
> What You mean with "localhost TFTP test"? When You run iptables firewall,
> You must consider EVERY connection, even if it is from tftp client running
> at same machine as tftp server (e.g. with command "tftp 127.0.0.1 -c get
> FILE").
> And it seems as Your tftp client run from machine with IP=192.168.0.5
> and server run at another with IP=192.168.0.4, right?
>
>
I have tried both localhost and from a remote machine.

> > How do I load conntrack_tftp ?
>
> You had it above - right "Fedora way" is specify module in file
> "/etc/sysconfig/iptables-config", as value of IPTABLES_MODULES variable:
>
> IPTABLES_MODULES="nf_conntrack_tftp"
>
> (and then restart Your firewall: "service iptables restart").
> But, for symplifying things (which is advisable, You solve this simple
> problem third day!), when it isn't security risk, You can stop firewall:
>

Okay loaded conntrack_tftp

>
> service iptables stop
>
> and run it again after verify tftp is OK without it.
>

No its not working without iptables, tried this many times.

>
>
> > > > > 5) /var/log/messages should contain entries as:
> > > > > Oct 10 20:28:32 ns xinetd[1908]: START: tftp
> pid=5315 from=192.168.1.22
> > > > > Oct 10 20:28:42 ns xinetd[1908]: EXIT: tftp
> status=0 pid=5315
> > duration=10(sec)
> > > > >
> > > > >
> > > > > Oct 10 21:09:07 gold xinetd[13402]: Exiting...
> > > > > Oct 10 21:09:12 gold xinetd[13650]: xinetd Version
> 2.3.14 started with
> > libwrap loadavg
> > > > > labeled-networking options compiled in.
> > > > > Oct 10 21:09:12 gold xinetd[13650]: Started working: 1
> available service
> > > >
> > > > There isn't nothing about that xinetd starts tftp daemon.
> Mentioned
> > > > "1 available service" is tftp?
> > > > This command show only tftp:
> > > >
> > > > # grep '^[[:blank:]]*disable.*no' /etc/xinetd.d/*
> > > > /etc/xinetd.d/tftp: disable = no
> > > >
> > > >
> > > > I tested it and it is the only xinetd demon running
> > > >
> > > >
> > > > Next command display some similar at Your server?:
> > > > # netstat -a -n -p --ip|grep 69
> > > > udp 0 0 0.0.0.0:69 <http://0.0.0.0:69> <
> http://0.0.0.0:69>
> > 0.0.0.0:* 1595/xinetd
> >
> > What netstat now displays? Is xinetd listening at udp 69 ??
> >
> > [root@XXXX ang]# netstat -a -n -p --ip|grep 69
> > udp 0 0 0.0.0.0:69 0.0.0.0:* 1127/xinetd
>
> Okay, now when You connect with tftp client, You should see in
> /var/log/messages
> entries from xinetd daemon about starting tftp daemon.
>

Nothing in messages

Thanks for the help, I am thinking of escalating this to the development
group.

Aaron

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